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81.
Cristián Bravo Sebastián Maldonado 《The Journal of the Operational Research Society》2015,66(11):1895-1905
Dataset shift is present in almost all real-world applications, since most of them are constantly dealing with changing environments. Detecting fractures in datasets on time allows recalibrating the models before a significant decrease in the model’s performance is observed. Since small changes are normal in most applications and do not justify the efforts that a model recalibration requires, we are only interested in identifying those changes that are critical for the correct functioning of the model. In this work we propose a model-dependent backtesting strategy designed to identify significant changes in the covariates, relating a confidence zone of the change to a maximal deviance measure obtained from the coefficients of the model. Using logistic regression as a predictive approach, we performed experiments on simulated data, and on a real-world credit scoring dataset. The results show that the proposed method has better performance than traditional approaches, consistently identifying major changes in variables while taking into account important characteristics of the problem, such as sample sizes and variances, and uncertainty in the coefficients. 相似文献
82.
Artemis P. Guimarães Andreas Möller Reiner Staudt Diana C. S. de Azevedo Sebastião M. P. Lucena Célio L. Cavalcante Jr. 《Adsorption》2010,16(1-2):29-36
The diffusion behavior of C4–C10 n-alkanes in silicalite-1 has been investigated by using the Zero Length Column method. The diffusivities derived from measurements at different purge rates with different purge gases confirming intracrystalline diffusion control. Data are compared with results reported in the literature for MFI zeolites. The diffusivities were found to be consistent and agree well with data previous obtained by ZLC. However, these data showed a remarkable disagreement with other reported techniques (PFG-NMR, QENS and Permeation). The eventual influence of carbon dioxide (CO2) adsorption on diffusion properties of n-alkanes in silicalite was also investigated. For this purpose, a series of experiments was performed involving hydrocarbons mixed with CO2. Data were obtained at 303 K and flow rates between 20 and 80 mL/min. The presence of CO2 does not seem to influence the intracrystalline transport rate of the investigated light hydrocarbons (n-C4 and n-C6). On the other hand, the situation for n-C8 and n-C10 is more complex. The diffusivity values are higher compared to the previously reported values. 相似文献
83.
We report the synthesis of two novel Gd(III)-complexes derived from linear and macrocyclic polyaminopolycarboxylic acids 1 and 2, which contain a 3,5- dimethylpyrazolyl-ethyl arm, and a study of their relaxivity properties. The relationships between the experimental and theoretical results have provided interesting information about the kinetic and thermodynamic stability of these complexes. 相似文献
84.
Mariana Barturen Mahmoud Eddrieff Julián Milano Sebastián Bustingorry Horia Popescu Nicolas Jaouen Fausto Sirotti Massimiliano Marangolo 《The European Physical Journal B - Condensed Matter and Complex Systems》2013,86(4):191
We show by a combined magnetic force microscopy and synchrotron radiation spectroscopy study that stripe-like patterned magnetic domains are present in Fe1?x Ga x thin films. These stripes, whose origin is attributed to an out-of-plane magnetic component, can be rotated by an external magnetic field. 相似文献
85.
Truzzi DR Ferreira AG da Silva SC Castellano EE Lima FC Franco DW 《Dalton transactions (Cambridge, England : 2003)》2011,40(48):12917-12925
The trans-[Ru(NO)(NH(3))(4)(P(OH)(3))]Cl(3) complex was synthesized by reacting [Ru(H(2)O)(NH(3))(5)](2+) with H(3)PO(3) and characterized by spectroscopic ((31)P-NMR, δ = 68 ppm) and spectrophotometric techniques (λ = 525 nm, ε = 20 L mol(-1) cm(-1); λ = 319 nm, ε = 773 L mol(-1) cm(-1); λ = 241 nm, ε = 1385 L mol(-1) cm(-1); ν(NO(+)) = 1879 cm(-1)). A pK(a) of 0.74 was determined from infrared measurements as a function of pH for the reaction: trans-[Ru(NO)(NH(3))(4)(P(OH)(3))](3+) + H(2)O ? trans-[Ru(NO)(NH(3))(4)(P(O(-))(OH)(2))](2+) + H(3)O(+). According to (31)P-NMR, IR, UV-vis, cyclic voltammetry and ab initio calculation data, upon deprotonation, trans-[Ru(NO)(NH(3))(4)(P(OH)(3))](3+) yields the O-bonded linkage isomer trans- [Ru(NO)(NH(3))(4)(OP(OH)(2))](2+), then the trans-[Ru(NO)(NH(3))(4)(OP(H)(OH)(2))](3+) decays to give the final products H(3)PO(3) and trans-[Ru(NO)(NH(3))(4)(H(2)O)](3+). The dissociation of phosphorous acid from the [Ru(NO)(NH(3))(4)](3+) moiety is pH dependent (k(obs) = 2.1 × 10(-4) s(-1) at pH 3.0, 25 °C). 相似文献
86.
Kirstene A. Gultian Roshni Gandhi Tae Won B. Kim Sebastián L. Vega 《Macromolecular bioscience》2023,23(3):2200425
Although photopolymerization reactions are commonly used to form hydrogels, these strategies rely on light and may not be suitable for delivering therapeutics in a minimally invasive manner. Here, hyaluronic acid (HA) macromers are modified with norbornene (Nor) or tetrazine (Tet) and upon mixing click into covalently crosslinked Nor-Tet hydrogels via a Diels–Alder reaction. By incorporating a high degree of Nor and Tet substitution, Nor-Tet hydrogels with a broad range in elastic moduli (5 to 30 kPa) and fast gelation times (1 to 5 min) are achieved. By pre-coupling methacrylated HANor macromers with thiolated peptides via a Michael addition reaction, Nor-Tet hydrogels are peptide-functionalized without affecting their physical properties. Mesenchymal stem cells (MSCs) on RGD-functionalized Nor-Tet hydrogels adhere and exhibit stiffness-dependent differences in matrix mechanosensing. Fluid properties of Nor-Tet hydrogel solutions allow for injections through narrow syringe needles and can locally deliver viable cells and peptides. Substituting HA with enzymatically degradable gelatin also results in cell-responsive Nor-Tet hydrogels, and MSCs encapsulated in Nor-Tet hydrogels preferentially differentiate into adipocytes or osteoblasts, based on 3D cellular spreading regulated by stable (HA) and degradable (gelatin) macromers. 相似文献
87.
Felix Geist Dr. Sebastián Martínez Dr. Jacqueline Ramler Dr. Kai Oberdorf Lisa Brändler Sascha Reith Prof. Dr. Crispin Lichtenberg 《欧洲无机化学杂志》2023,26(32):e202300546
Bis[dibenzobismepine], a dibismuthane composed of two bismepine units (R2Bi−BiR2), was synthesized and fully characterized (R2=(C6H4CH)2). Reactions of this dibismuthane with diphenyl dichalcogenides, dibenzoylperoxide, and elemental chalcogens have been investigated. All products of these reactions have been isolated and fully characterized, including a series of compounds R2Bi−E−BiR2 (E=O−Te). These species contain two olefin units of the bismepine moieties and a chalcogen atom as potential coordination sites. The potential of these species to act as hybrid tridentate chalcogen/olefin ligands with bismuth atoms as structure-determining elements in the backbone has been investigated by theoretical approaches, aiming at the complexation of CoI, RhI, IrI and Ni0, Pd0, Pt0. The analytical techniques applied in this work include heteronuclear and 2D NMR spectroscopy, elemental analysis, single-crystal X-ray diffraction analysis, and DFT calculations. 相似文献
88.
Johan Sebastián Díaz Tovar Dr. Giulia Kassab Dr. Natalia Mayumi Inada Prof. Dr. Vanderlei Salvador Bagnato Prof. Dr. Cristina Kurachi 《Chemphyschem》2023,24(18):e202300381
Indocyanine green is an attractive molecule for photodynamic therapy due to its near infrared absorption, resulting in a higher tissue penetration. However, its quantum yields of the triplet and singlet state have been reported to be low and then, reactive oxygen species are unlikely to be formed. Aiming to understand the ICG role in photodynamic response, its photobleaching behavior in solution has been studied under distinct conditions of CW laser irradiation at 780 and 808 nm, oxygen saturations and solvents. Sensitizer bleaching and photoproduct formation were measured by absorption spectroscopy and analyzed using the PDT bleaching macroscopic model to extract physical parameters. ICG photobleaching occurs even at lower oxygen concentrations, indicating that the molecule presents more than one way of degradation. Photoproducts were produced even in solution of less than 4 % oxygen saturation for both solvents and excitation wavelengths. Also, the amplitude of absorption related to J-dimers was increased during irradiation, but only in 50 % PBS solution. The formation of photoproducts was enhanced in the presence of J-type dimers under low oxygen concentration, and the quantum yields of triplet and singlet states were one order of magnitude and two times higher, respectively, when compared to ICG in distilled H2O. 相似文献
89.
Fabrício N. Costa Sebastián Urrutia Celso C. Ribeiro 《Annals of Operations Research》2012,194(1):137-150
The Traveling Tournament Problem with Predefined Venues (TTPPV) is a single round robin variant of the Traveling Tournament Problem, in which the venue of each game to be played is known beforehand. We propose an Iterated Local Search (ILS) heuristic for solving real-size instances of the TTPPV, based on two types of moves. Initial solutions are derived from an edge coloring algorithm applied to complete graphs. We showed that canonical edge colorings should not be used as initial solutions in some situations. Instead, the use of Vizing’s edge coloring method lead to considerably better results. We also establish that the solution space defined by some commonly used neighborhoods in the sport scheduling literature is not connected in the case of single round robin tournaments, which explains the hardness of finding high quality solutions to some problem instances. Computational results show that the new ILS heuristic performs much better than heuristics based on integer programming and that it improves the best known solutions for benchmark instances. 相似文献
90.
Geometriae Dedicata - Let $$m ge 6$$ be an even integer. In this short note we prove that the Jacobian variety of a quasiplatonic Riemann surface with associated group of automorphisms isomorphic... 相似文献